Wireless communications devices, such as cellular telephones, have become extremely popular with business and personal users. The manufacturers of wireless communications devices typically provide a time-limited warranty with their products. The warranty typically guarantees to purchasers that the manufacturer will repair or replace a defective wireless communications device for free during a set period of time, such as one year from purchase. After the warranty period has expired, any repair costs are the financial responsibility of the wireless communications device owner, not the manufacturer. Because costs of warranty repair and replacement are significant, manufacturers are keenly interested in determining whether the warranty period has expired or not.
Most warranty periods for wireless communications devices begin to run at the time of purchase. Customers usually purchase wireless communications devices from a retail outlet. After purchase, a cellular telephone network service provider activates the telephone to allow the phone to access the service provider's wireless communications system.
Because manufacturers generally do not own or control the retail outlets and service providers, the manufacturer typically loses track of the wireless communications device once the manufacturer ships the device to the retail outlet. As such, manufacturers have difficulty in determining when the wireless communications device is sold to a consumer. Several different methods and systems for tracking when a particular wireless communications device was first sold to a customer have been tried, but with limited success.
One approach is to require the purchaser of the wireless communications device to mail a warranty card to the manufacturer. This approach has met with consumer dissatisfaction and, because consumers are not required to return the warranty card in order to recover under the warranty, many fail to do so. Further, by accident or with fraudulent intent, the consumer may simply record the wrong date on the warranty card.
A second approach is to require the consumer to provide proof-of-purchase documentation such as a sales slip when requesting warranty service. This method, however, puts a considerable burden on the consumer to maintain and locate the sales slip some time after the purchase of the wireless communications device, and is therefore not well received by consumers.
A third approach is for the manufacturer to estimate the wireless communications device's sales date based on the device's known date of manufacture along with the average inventory time for a particular service provider or equipment vendor. This method has the disadvantage of highly dubious accuracy, and therefore frequently induces the manufacturer to err to the consumer's benefit in the spirit of good customer relations by providing warranty service long past the actual date on which the warranty should have expired.
Still another approach is for the wireless communications device to record its own start-of-service date in internal non-volatile memory. The manufacturer then reads this date when examining a wireless communications device returned for warranty service. This method, although clearly an improvement on the earlier methods, nevertheless has two disadvantages: (1) the user or service provider must enter the start-of-service date, or the wireless communications device must contain a calendar so that it has a sense of time and is therefore cognizant of its start-of-service date, and (2) the date held in non-volatile memory may be obliterated in the case of catastrophic failure, and may therefore be unavailable to the manufacturer at the time warranty service is requested.
These and other shortcomings of the prior art suggest that there remains the need for a simple, effective method for determining the warranty period for a wireless communications device.